Hydraulic piston-control rigging for refrigerator-compressors



Jan. 22, 1952 o. ZEHNDER HYDRAULIC PISTON-CONTROI.. RIGGING Patented Jan. 22, 1.952

HYDRAULIC VPI-STON-CON'IROL RIGGING FOB ,BEFRIGERATOR-COMPRESSORS Otto Zehnder, Granichen, Switzerland, assignor to Gebruder Zehnder Radiatoren- &VAppara tebau, Granichen, Switzerland -Y I `Application March 28, 1946,'Seral No. 657,748 In Switzerland April 3, 1945 3'Claims. 1

The invention relates to a refrigerator of the compressor-condenser-expander type, in which the inlet or lling stroke of the compressor piston is effected by the pressure of the refrigerating medium vapour, and the compression stroke of the compressor piston is eiected by an automatically cut-in auxiliary force.

It is known to provide as the auxiliary force an electric motor which operates a lifting device provided for the compressor piston.

Contrary to this, according to the invention a driving piston cooperates with the compressor piston in such manner that it follows the inlet stroke of the compressor piston and effects the compression stroke of the latter, the driving piston being moved by means of :liquid under pressure which s automatically controlled as desired. This permits of a p-articularly cheap construction of the refrigerating installation Vin respect of manufacturing and maintenance costs.

The accompanying drawing shows partly in section and partly diagrammatically, as an example, one way of carrying out the invention.v

In a cylinder I is a piston 2 serving for compressing the refrigerating medium At its upper end, the cylinder I is connected by pipes3 and 4 to the upper end of an 'evaporator or expander and a condenser or liqueer, not shown. Liquid refrigerating medium supplied is evaporated in the expander with absorption of heat, and liquefied in the condenser with emission of heat. Expander and `condenser are connected together at the lower end by a pipe in which there is tted a throttle valve controlled by a oat or by temperature responsive means, not shown. A springloaded inlet valve 5 and a spring-loaded outletl valve 6 are arranged in the upper end of the cylinder` I. Connected coaxially to the lower end of the compressorcylinder I is a pressure cylinder "I, in which is a driving piston 8 kept ata-distance from the compressorpiston 2 by means ofV a rod 9. The driving piston 8 is constructed as a hollow cylinder which, on its downward movement, slides over a filling inset I0 provided in the-pressure cylinder l and which at the same time serves for limiting the downward stroke of the driving piston 8 and thus of the compressor piston 2.

A main pipe II leading from a storage container, not shown, of the drivingliquid is connected to the lower end of the pressure cylinder 1, and a gear pump I2 or other kind'of conveyor pump is connected in this pipe and'is adapted to be driven preferably by an electric motor. The main pipe I I is also connected through a branch pipe I3, in which is iitted a non-return valve- I4".-*

-ing as an abutment for the spring Il.

Vthe main pipe II with an auxiliary cylinder I5 in which there is'a piston |6. On this piston I6 a compression spring I1 acts, the tension of which is adjustable by means of a screw I8 which carries a plate I9 serv- To the pressure cylinder 'l there is connected, by means of an outflow pipe 20, a subsidiary cylinder 2| in which there is a double piston 22, 23 acted on by a compression spring 24. spring 2t is adjustable by means of a screw 25 which holds a plate 26 serving as an abutment for the spring 2li. Between the branch pipe I3 and the subsidiary cylinder 2| there is provided a connecting pipe 2l. rectly from the main pipe II to the subsidiary cylinder 2| which, by means of two return pipes 2S and 30 connected thereon at different levels, directly communicates with the storage reservoir 39 of the pressure liquid. The pressure cylinder 'l also communicates by a return pipe 3| directly with the said storage reservoir 39.

Assuming that the driving piston 8 provided inY the pressure cylinder 'I is moved upwards by the liquid under pressure, e. g. oil, delivered by means of the pump I2 through the main pipe to the pressure cylinder 1, this movement is transmitted by the rod 9 to the compressor piston 2 which forces the gas in the compressor cylinder I through the valve 6 and the pipe 4 into the condenser. At the working position indi-cated, no liquid underpressure can pass out of the branch pipe 28 leading from the main pipe II, into the subsidiary cylinder ZI, since the aperture 32 in question on the subsidiary cylinder 2| is closed by the upper piston 23 of the double piston 22, 23. On the contrary, fluid under pressure ows through the branch pipe I3 also running from (and through its non-return valve I4) to the auxiliary cylinder I5, so that the piston I6 is moved upwards overcoming the counterforce exerted by the compression spring I1. When the upwardly moving driving piston 8 in the pressure cylinder 'l uncovers the aperture or port 33 thereof to the outiiow pipe 2D, liquid under pressure ilows into the subsidiary cylinder 2| whereby the double piston 22, 23 is moved upwardly therein, overcoming the counterforce exerted by the compression spring 24. Afterwards the apertures 32 and 34 in the subsidiary cylinder 2| are simultaneously opened by the upwardly moving double piston 22, 23. In this way the outflow pipe 2|] is connected through the inner space of the subsidiary cylinder 2|, the opening 34 and the connecting pipe 21 to the branch pipe I3; the non-return valve I4 provided in the latter pre- The tension of the A branch pipe 28 leads disidiary cylinderZI; so that liquid under pressure.

now flows out of the auxiliary cylinder I5, the

compression spring I1 expanding and the pistonf.

I6 moving downward forcing liquid through the connecting pipe 21 into the subsidiarycylinderl 2I j thus assisting the further upward movement4 of" its double piston 22, 23 which consequentlyiinallyJ completely uncovers, in the subsidiary cylinder.2 I ,-1, the opening 35 of the return pipe 29 leadingto the storage reservoir 39 and the opening 32 of the branch pipe 28. Thus by reversinglthfe `flowof-'thefliquid under pressure and causing it to'flowbackf into the storage reservoir 39 at a predetermined upper terminal position offthe compressor piston 2,.,the reversal of itsdirectionof movement has.

beencompleted... Followingthereafter, the com.-

pressorl piston 2 .'is moved Adownwards under. the-A pressureeftect of thecooling medium .vapour owing from the. expander through the. pipe 3 into. the compressor cylinder I.

The driving: piston 8.accompanies Vthis movement..,whereb`yitcloses .the aperture 33 provided inlthe pressurecylinder 1, andthus no liquid under pressure flows anylongerthrough the branch pipe .20. to the auxiliarycylinder 2 E.

auxiliaryfcylinder 24,by the liquid under pressure,

rst stays in its vcorresponding upperposition as.

below therlower piston 22 of the doubler-piston 22;, 23 then flows with the slacking of the compression..

spring-24 andfcorresponding downward movement of said` double piston,out of the auxiliary `cylinder 2I -through-the outletpipe 20 to the pressurev cyl- The annular space formed bymeans of inder 1. the circumferential. groove36 ofy the driving cyl--` inder' -between thelatter and the-inner wall-fof the pressure cylinder1, also extends over an `opening ;31zin the pressurecylinder 1 associated with the return pipe- 3I,= so that the liquid under-pres-` sureowingr-into this annular space through thev outlet-Y pipe=1f20iromthe subsidiary cylinder '2 I makes its way-through thesaid annular spacefand theaperture 31 into the-return pipe 3I to fiowto Consequently, the aperthe; 'storage` container. tures35 and `32-in`thesubsidiary cylinder 2If-.for the :return pipe 29 and the branch pipe 28 respectively, are-.again. closed byjfthe upper pistonA -23- ofi-the. downwardly `.movingdouble piston -.22,. 23 as-Aalso, by the lower pistonA 22, the aperturef34 v2of:

the connecting pipe 21, whereupon' liquid under pressureisagain `forced. by.thepump,I2 into4 the pressure cylinder 1 and into` the auxiliary cylinder I5,'sor` that inthe former. (1) the driving .piston 8,.

together 4with the compressor piston 2,v and rin-the latter.l (I5) thepiston I6 are againmoved up.-` wards.v The cycle described `is repeated as.,re

quired for the purpose of maintaining a predeter.- mined temperature.

During `the working cycle describedi Vthe pressure of the refrigerating medium vapour natural.-v

1ydropsand .the temperature .falls 4 so .that iinally,

The double pistorr 22, 23 .previously moved upwards inv thev an inserted regulator eiects a current interruption to the motor, and working ceases. The Working cycle is again initiated when the temperature in a refrigerating cabinet tted with the compression refrigerating installation described rises, fory examplei'by--a prolonged opening thereof,f"to-say;41`C., whereuponthe.te'mperature regulator referred to again throws in the electric motor so that the cycle of operations again commences.

'I'lieparticularlygsimple design of the refrigeratin'giinstallatini-permits of operating with a specially low .numbenof strokes and consequently large@cylinderrcapacity, so that with large dimensioningiot theiexpander surface the expander pressurelcank no, longer fall, for example, more than" atm during an inlet stroke of the comprssr'pistn.

A'Lthrottling device can be mounted in the return pipe 29 leaving the subsidiary cylinder 2 I, in order Ato permit the return i'lowfof the liquidunder pressuref'to thev storage container, and thusfto` regulate-the" falling; or-I inletfmovement of the rf compressor. piston 2.l

Whatf-I :claim:andzfdesireeto secure :byy Letters i Patentisz.l

1. A piston compressor typefofl refrigeratingfI plantzcomprisingza compressor Ahaving-a:.cylinder and agpistom, the Lllingrstroke: ofcwhichliszproe -A duced by the pressurefroffthevvapor'of;'expanded refrigerante@ motor rfh'aving( fanioperative .rpiston drivingly' 'connected l with i the'zcompressor pistorr': to produce :the discharging :stroke :ofthe compres-1r 1 sor rpiston', while the said' :drivingt'piston partakes?y of `thecmotion ,of hetcompressor pistonf-in. its fiill-- ing: stroke;` thereby'being :displaced inizthedriving-L motor, said :motor: havingz a.. pressure. cylinder-inf; which the-drivingfpistoni isf-located, a supply res-f ervoir, for:y operating rliquid,vvv apressurexpump for:- supplying driving,..pressure` fliquidpto the driving: motor; a @supply conduit Aconnecting saidVv pump with-said motor cylinder; .as subsidiary cylinder,-y an auxiliary cylinder; the vsubsidiarycylinder:and: the :auxiliarygcylinder-.each 'being provided 'with A afspringgloaded. piston; a .conduit :connecting the-f drivingmotor at 1' an f intermediate point z of its stroke with the subsidiary ,fcylinder on-l the oppo- I sitetside of-;itsf:.pistonfrom its .loadingspring1,.V af: conduit connecting-....:the: auxiliary; cylinder' at point 'on theiopposites-side fofitsrcylinder from its loadingfspringfwithamoint of thesubsidiary cylin; der whichis blockedzbyits pistoriwhenits spring.' is;fu1ly.fexpanded.and is' opened whenfthe piston-- moves to compressi-its spring, so :that :the auxiliary; piston: is .thenf suppliedY withl driving:liquid, return` pipesfleadingdrom: :thecylinderof :theoperating motor-andv from the r subsidiary ,i cylinder tofthe supplymeservoir .the piston in the-auxiliary cyli'ns4 der therefore;-,being moved.v against-:the force :cfr itspiston.` loading; spring.; during; the: pressuref strokeof l`the operatingpistonf,and.at the end f of.. the; stroke.` forcing,- pressure.;iiuid.v from the motor cylindentozfthefnsubsidiary cylinder;vv and y movingethe:subsidiaryxcylinder piston against the i force ofdts piston loading springy tot` thereby .connect the vauxiliary. cylinder with the subsidiary f cylinder and by-means-oi the-subsidiary-cylinderf piston openY the proper return pipe so as tochange thevcompressor-piston over to fillingv stroke, the. returning. operating .1 piston being.. thereupon 1 at i. rst temporarily;- cut 01T from the pressurey cylin der and-thereupon connectedwithfitsreturn pipe-,1., the :piston vofthe-subsidiary cylindery being then movedby its.sprir1g-.and,serving'Lto cutithe sub-y cylinderm oi-fffrom.. the fauxi-liary cylinder and to close the return pipe of the subsidiary cylinder, thus producing the discharging stroke of the operating piston and again supplying pressure liquid to the auxiliary cylinder.

2. Refrigerating apparatus according to claim 1, and in which the piston in the subsidiary cylinder is a double headed piston, one of which heads of said double piston serves for controlling a connecting pipe provided between the subsidiary cylinder and the auxiliary cylinder and a check valve in the supply pipe of the auxiliary cylinder.

3. Refrigerating apparatus according to claim l, and in which the operating piston is provided `sith a peripheral groove for effecting connection of the return pipe of the pressure cylinder with the subsidiary cylinder so as to connect subsidiary cylinder with the liquid reservoir to allow dis charge of the subsidiary cylinder to the reservoir.

OTTO ZEHNDER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,075,922 Zehnder Apr. 6, 1937 2,340,034 Zehnder Jan. 25, 1944 FOREIGN PATENTS Number Country Date 633,104 Germany July 20, 1935 

